The present invention relates to frequency dependent dampers or shock absorbers, and more particularly to a booster to adapt air spring pressure for a frequency dependent damper or shock absorber.
Shock absorbers are used in conjunction with automotive suspension systems to absorb unwanted vibrations which occur during driving. To absorb these unwanted vibrations, shock absorbers are generally connected between the sprung portion (body) and the unsprung portion (suspension) of the automobile. A piston is located within a pressure tube of the shock absorber and the pressure tube is normally attached to the unsprung portion of the vehicle. The piston is normally attached to the sprung portion of the vehicle through a piston rod which extends through the pressure tube. The piston divides the pressure tube into an upper working chamber and a lower working chamber. The shock absorber, by restricting fluid flow between the upper and lower working chambers, produces a damping force that counteracts the vibration that would otherwise be transmitted from the unsprung portion of the vehicle to the sprung portion of the vehicle.
Spring devices are implemented with the shock absorbers to resiliently support the vehicle on the suspension system. Exemplary spring devices include coil springs, torsion bars and air springs. As the vehicle load increases the spring devices compress. The dampening capability of the shock absorbers, however, remains constant regardless of the vehicle load. While a constant dampening ability may be acceptable in some applications, other applications would benefit from a shock absorber whose dampening characteristics vary with vehicle load.
Accordingly, the present invention provides a suspension system for a vehicle, which includes a shock absorber with variable dampening capability. The suspension system includes a frequency dependent damper (FDD) or shock absorber defining a first pressurized working chamber. An air spring assembly defines a second pressurized working chamber. A booster enables pressure communication between the first pressurized working chamber and the second pressurized working chamber.
In one feature, the booster includes a housing defining segmented chambers and a piston assembly slidably disposed within the segmented chambers. The piston assembly includes a first piston dividing a first segmented chamber and a second segmented chamber. A second piston is interconnected with the first piston and divides the second segmented chamber and a third segmented chamber. The first segmented chamber is in fluid communication with the second pressurized working chamber. The third working chamber is in fluid communication with the first pressurized working chamber. The first piston is of a larger diameter than the second piston.
In another feature, a restrictor is disposed between the air spring assembly and the booster to inhibit pressurized fluid flow therebetween.
In still another feature, the suspension system further includes a limiter that limits operation of the booster.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.